1. Field of the Invention
This invention relates to a blood analyzing system for analyzing the amount of a component such as glucose which is present in a blood sample.
2. Description of the Related Art
The components of blood collected from a man or animal are measured to check his or its health.
The components such as glucose, LHD (lactate dehydrogenase) and neutral fat are usually measured and analyzed for the foregoing purpose. Hereinafter, a component to be measured and analyzed is called the "specified component."
The specified component is usually measured as described below. A drop of a blood sample (e.g. centrifugally separated serum or plasma) is applied onto a glass test slide coated with a reagent on its upper side. Reacting to the reagent, the dropped blood is colored or changes its color. In a certain period of time, light is irradiated onto the test slide. The light reflected from or passing through the test slide is received, so that the level of content of the specified component can be calculated according to intensity of the light having a particular wavelength. One example of measuring instruments for this purpose is disclosed in a Japanese Patent Laid-Open Publication No. Sho 62-194442.
To analyze the component accurately, a known volume of the blood sample should be applied onto the test slide. When it is manually applied by a pipet, the volume of the blood sample will become variable, thereby making the analysis less reliable.
Japanese Utility Model Laid Open Publication No. Hei 2-17662 discloses a pipet unit for applying the blood sample. The pipet unit sucks and transfers the blood sample by the pump action exerted by a piston and a cylinder. The volume of the blood sample can be more accurately controlled than when the sample is manually transferred. In the cited invention, the piston is operated by a piston actuator.
With the conventional pipet unit, the volume of the blood sample actually transferred is not measured at all. If the piston stroke happened to become irregular temporarily or intermittently, the transferred volume of the blood sample would deviate from the present volume. Therefore, it is necessary to correct errors in the analyzed results due to inaccurate volumes of the blood samples.
In addition, the volume of the applied blood sample is variable because the piston stroke sometimes becomes irregular due to backlash resulting from relative motion of gears caused by looseness in the piston actuator. Therefore, it is necessary to remove such backlash as much as possible.